Highs today will be about a cool as we'll see all week long, topping out near 108 as high pressure has retreated to the East a bit.
With that, air quality has hovered in the "Moderate" range, and will do so through tomorrow into Friday.
That area of high pressure will retrograde back toward Southern California as we move toward the weekend. That will increase temps going into Friday.
That will prompt an Excessive Heat Watch (likely becoming a Warning by Saturday morning) which will last through the weekend.
The weekend will offer up the hottest temps we've seen all year, with highs approaching 120 degrees into early next week.